Implement and manage virtual networking

The correct answer is to Manually add the specific IP addresses to the network adapter configuration inside the guest operating system.

When adding secondary private IP configurations to an Azure virtual machine's network interface, distinct steps must be taken at both the Azure infrastructure level and within the guest operating system. While the Azure portal update successfully reserves the IP addresses and associates them with the interface physically, the Azure DHCP service, which configures the VM's network interface upon boot, typically only assigns the primary IP configuration automatically.

Therefore, the guest operating system remains unaware of the additional IP addresses. To fix this, an administrator must log into the virtual machine and manually configure the static IP addresses on the network adapter within the OS settings (such as Windows TCP/IP properties or Linux network configuration files). Once manually added, the OS will recognize the interfaces, and applications can successfully bind to them.

Why the other answers are incorrect:
- Restarting the virtual machine instance will not solve the problem because the Azure DHCP service does not automatically assign secondary IP configurations to the guest OS; the OS will still only receive the primary IP address upon reboot.
- Enabling IP forwarding is a configuration used when a VM acts as a network virtual appliance (like a router or firewall) to handle traffic meant for other destinations. It does not enable the local OS to utilize secondary IPs for its own applications.
- Associating Public IP addresses relates to external internet connectivity. While secondary configurations can have Public IPs, this action does not configure the internal guest OS network stack to recognize the underlying private IP addresses necessary for the application binding.

The correct configuration is to create an outbound Network Security Group (NSG) rule permitting the 'Storage' service tag.

When you enable a Service Endpoint for Microsoft.Storage, a route is added to the subnet to direct traffic to the storage service via the Azure backbone network. However, Service Endpoints do not bypass NSG rules. Since your NSG explicitly blocks all outbound internet traffic, and Azure Storage public endpoints are technically part of the internet IP space, the traffic is dropped by the NSG before it leaves the subnet. To fix this, you must add a higher-priority rule allowing outbound traffic to the 'Storage' Service Tag. This tag dynamically manages the list of IP addresses used by Azure Storage, allowing access to the service while maintaining the general internet block.

Regarding the incorrect answers:
- Modifying the route table to point the next hop to the Virtual Network Gateway is incorrect because Service Endpoints are designed to route traffic directly to the Azure service, not through a gateway.
- Configuring the storage firewall to allow the subnet's public IP is incorrect because the immediate issue is the NSG blocking outbound traffic at the source. Furthermore, when using Service Endpoints, the storage account sees the traffic coming from the VNet identity or private IP space, not a public IP.
- Associating an Application Security Group (ASG) with the storage account is not possible; ASGs are used to group Virtual Machine network interfaces for easier rule management and cannot be applied to PaaS resources like Storage Accounts.

The correct answer is that the IP address range must reside within the defined virtual network address space.

When you create a subnet within an Azure Virtual Network (VNet), the subnet effectively segments the VNet's larger IP address block into smaller chunks. Therefore, valid subnet ranges are strictly mathematically constrained to be subsets of the address space defined at the VNet level. You cannot define a subnet range that exists outside or exceeds the boundaries of the parent Virtual Network.

The other options are incorrect because subnets cannot exceed the VNet's capacity, should ideally not overlap with on-premises networks to ensure proper routing in hybrid scenarios, and typically utilize private IP ranges rather than dedicated public IP prefixes for internal segementation.